1. Field of the Invention
The present invention relates to an intervertebral fusion cage which may be inserted between vertebrae from which a disk is removed to restore and maintain an interval between two vertebrae, and more specifically, to an intervertebral fusion cage having an easily mountable shape while enlarging a contact area with blood in a spinal cavity during surgery.
2. Description of the Related Art
A vertebral body includes 32 to 35 vertebrae forming a body, and intervertebral disks, i.e., spinal disks arranged between the vertebrae, and is a portion forming a backbone of a human body that connects an upper skull and a lower pelvis to form the pillar of the truncus. The spine includes 7 cervical vertebrae, 12 thoracic vertebrae, 5 lumbar vertebrae, 5 sacra, and 3 to 5 coccyges from the top. In the case of an adult, 5 sacra are fused together to form one sacral vertebra, and 3 to 5 coccyges are fused together to form one tailbone.
When the intervertebral disc is deteriorated, a prosthesis referred to as an intervertebral cage is used for restoring a distance between two adjacent vertebrae. The intervertebral cage fuses such vertebrae so as not to be moved relative to each other through the growth of a bone graft inserted into the intervertebral cage, in an intervertebral cavity.
Spondylolisthesis refers to a state in which the fourth and fifth lumbar vertebrae are completely displaced due to a damage occurred in the vertebral body. In order to treat the spondylolisthesis, surgery using a so-called anterior lumbar interbody fusion (ALIF) has been performed. Herein, as a conventional cage commonly used in the ALIF, a rectangular box-shaped cage is mainly used. In this case, since the rectangular box-shaped cage is formed to have a significantly longer lateral length than a longitudinal length, in order to insert it between the vertebrae, the surgical site should be largely exposed, and the disk should be cut in a large region. Therefore, there are problems of difficulty in the surgery and the process being very time-consuming.
In order to solve these problems, a lateral cage has been developed and used for intervertebral disc surgery (see Korean Patent Laid-Open Publication No. 10-2011-0013651). However, since such a lateral cage has a smaller surface area than the ALIF cage, the contacting area with the blood in the spinal cavity is decreased, such that a relatively long time is consumed for fusing the vertebrae, and thereby, a relatively long recovery time is required for the patient after surgery.
In addition, the lateral cage is provided with one end portion which is firstly inserted into the vertebra of the patient during surgery and has a height formed substantially the same as the other portions. Therefore, in order to insert the one end portion of the lateral cage between the vertebrae, there is a need to apply a great force, and even when being put under an anesthesia, the pain felt by the patient is large.
Meanwhile, Korean Patent Laid-Open Publication No. 10-2014-0018668 discloses a cage having a blade mounted and fixed between intervertebral disks, but this cage still entails the above-described problems due to a configurational limitation.